Process and apparatus for casting ceramic articles



Oct. 11, 1932. B. s. PURINTON PROCESS AND APPARATUS FOR CASTING CERAMICARTICLES 1931 2 Sheets-Sheet 1 Filed July 27 I C r r //I n INVENTOR Oct.11, 1932. B. s. PURINTON 1,832,191

PROCESS AND APPARATUS FOR CASTING CERAMIC ARTICLES 2 Sheets-Sheet 2 ledJuly 27, 1931 INVENTOR Patented Oct. 11, 1932 Lima TEN 1:0 FF! I BERNARDs aun n'rongor EAST LIVERPOOL, OHIO "rnoonss ANnArPnBATns non cAsTINGCERAMIUARTICLCES 7 Application filed July 27, 1931. SerialNo. 553,28d. v

The presentinvention relates to...the casting of ceramic articles, andmore especially to the casting ofceramic. articles such as chinaware,porcelain and semi-porcelain tableware, in water absorbentmoldsi In theceramic industrytableware articles, such as pitchers,covered dishes,casseroles, and like shapes, which cannot be made on a jigger, areusually made by casting in water absorbent plaster of Paris molds. Afluid slip of ceramic. material is poured by the. workmen into the moldand allowed to stand therein until the workman judges that sufficienttime has elapsed for a. semi-solidcoherent layer of the ceramic materialto have become deposited against the walls of the mold due to theabsorption of .the water from the slip. The workman then pours out theexcess slip. The mold and its contained semis solid layer of ceramicmaterial therein is allowedto dry. The mold is then opened and thearticle, such as the: pitcher or dish, is re.- moved and finished byapplying the glaze and firing.

' blisters, strains, etc.

This process as carriedout in the manufacturing plant is .a handoperation, the, molds being filled and emptied by workmen. The thicknessof the walls of the article is determined by the judgment of the workmanin emptying the excess slip after he believes that sufficient time haselapsed for a layer. of proper thicknessto become deposited .in,themold.

The labor cost of making articles by this 51 casting method is so highthat it :haisben limited to the making of those articlessuch ascasseroles, covered dishes, pitchers, etc., whichcannot be-made on arotary table or jigger. Cups, plates, and the like,'are usually. made ona rotary table: or jigg er from a bat of'plastic ceramicmaterial. Thejiggering process is cheaper than" the casting process and is thereforeused when possible, although the jiggeredproductis] inferior due to airThe object ofmy invention is to cheapen the; cost of productionby thecasting process, whereby it can be employed not only in .making articlessuch as pitchers, covered l sh and th l ut a so m k ng ps,

grammatically apparatus for carrying out plates, etc., which haveheretofore been generally made on a jigger. I

e In carrying out my process, a water absorbent mold, such as a plasterof Paris mold, is immersed in a bath of fluid ceramic slip which risesinto and fills the mold. The mold is allowed to remain in the slip bathfor a pre-- determined time and is then removed, allowing theexcess slipto drain from the mold. This process readily adapts itself for machineoperation, whereby the operations of dipping andremoving the molds fromthe slip can be carried out by machinery, thus doing away with manuallabor and predetermining the time of immersion and thereby accuratelycontrolling the thickness of the 7 layer deposited in the molds.

In-the drawings, there is illustrated diamy process. 1

In the illustrated embodiment of my inven tion, Figure l is a bottomplanview of a set of plaster of Paris cup molds;-

.FigureQ is a section along the line 11-11 of.-Figurel;' a

Figure 3 is a vertical section through the molds along the line HIT ofFigure lillus- "tinting the molds as immersed in the tank or S P";

Figure 4 illustrates a modification, being an interior view ofhalf of a"plate mold; and Figure 5 is a vertical sectionthrough a plate moldimmersed in a bath of slip.

- Referring to the illustrated embodiment of the invention illustratedin Figures 1, 2' and 3, a number of 'cup molds l are for-med in a slabor body 2 of water absorbent material, such as plaster of Paris. Themoldis used in an inverted position, as shown in the drawings. The topsof the mold cavities 1 have vent holes?) which allow the escape ofentrapped air when the molds are immersed in the slip bath. In Figure 3the molds are shown as dipped into a bath 4L of the usual ceramic slipheld in a tank 5. The set-of molds is dipped, preferably by machinery,into the bath i of slip. As illustrated in Figure 3, the molds are shownas resting on a grid 6 which allows the slip to enter the mold cavities"1.

The slip 41's the usual fluidslip,such as a is used in the hand plasterof Paris mold casting operation. It is formed by a water suspension of amixture of clay, feldspar and flint, together with small amounts ofsodaash and silicate of soda to help hold the clay mix in suspension.The slip is preparedin the usual way in a blunger and is poured intothetank 5.

.VVhen the molds l-are dipped into the bath of slip, the'slip risesand'fills the mold cavities, as shown in Figure The en-;v

trapped air escapes throughthevents 3. I

The plasterof Paris mold body, because of its water absorbentproperties, absorbs the faces, and causes a-semi-solid coherent layer ofthe ceram1cmater1al to collect against the at the places where this isnotiwished.

Water from theislip adjacentthe m'old surinnerfacesof'the molds, asindicatedatf? in Figure 3.7 The molds are allowed to remain in the bathof slip until this semi-solid coherent layer. of ceramic materialisformed to, the desired thickness for the walls of the article being"cast. Then the molds are re moved from the tank, preferably bymachinery. In removing the molds, they are usually'tilted'slightly toallow the air toenter at one .side of the bottom mold cavity opene ingsand the excess slip to run out andback into the bath. The moldswiththeir depositedlayers of ceramic mix are then dried, pref erably ina drying room.. The drying causes a slight shrinkage of the ceramic.material,

which permits the articles,]such as the cups in the illustratedembodiment, to be readv ily removed from the molds preparatory to beingfinished by glazing and firing. The; spines 8 formed by the materialwhich may enterthe vent openings 3 are readily 'cut off ofthe articles.

Since the height to the slip may rise in the vent openings 3 is.controlled byzthe depth to which the molds are dipped in the bath, thereis no wasting or escaping of the slipthrough the vent holes, as would bethe case in apressure casting operation.-

Asillustrated in Figures 1,2 and 3 of the drawings, the surfaces of themold cavities l and the top surface of the plaster of Paris slip 2areformedfromthe surface of the plaster of Paris, so that the moldcavities may absorb water and so that the water can be readily driedtherefrom at the top surface of themold body as wellf'as from themold'surfaces. The bottom surfaceeof' the mold body and the sidesurfaces are preferably coated or glazed with a waterproof 6 l 9 toprevent the deposit of the material This processadaptsjitself readliy tomachinev operation. The molds can be dipped into the tank of slip bymachinery and held therein for a predetermined time and thenautomatically removed, thus not only doing away with manual laborbutalso substituting mechanically timed operations for the V judgment ofthe operator" which is now relied" upon in the manual process. Therelatively large body of slip in the tank can be accu- I 'ratelycontrolled and maintained as to condi- .of Paris The inoldpavity; 12havin g the shape of aplate, is formed between the two. halves ofjthesplit mold YA bottom feeder openingil3and; side feeder openings ltzare.

provided for admission of'the fluid slip into the mold when it is dippedinto the slipibathai An air ventopeninglS is Tprovided'to allow-1 theescapeof'air trapped-in themold when it is immersed. The outer surfacesof the molds are preferably coated or glazed with a waterproof layer'16, whi'ch prevents the deposit of-the slip material at places wherethis is not wished; As shownin Figure 5,"the .mold is immersed in a bath17 of fluid slip whichiby. its natural hydraulic pressure feeds itselfthrough the feed openings 13' and 14; to sup-:1 ply the ceramic materialwhich solidifies into asemi-solid coherent mass within the mold cavitydue to the absorption of the-water from the slip by thewater absorbentplaster of'Parisl :Afterthis coherent semi-fluid body of ceramicmaterial is formed from the slip within the mold, the mold is removedfrom the bathand-opened, and the bod; of the plate 18" is'allowed' "todry' andis then removed fromthe mold ing by glazing and firing WVhile Ihaveillustrated scope of thefollowi g l p .e

fI'claim: 1. Theprocess of c open at its bottom, ventingthe air trappedin'the mold andfcausing theslip to-ri'seinto and fill the mold cavityand remain therein from the bath. j y a ceramic slip a water absorbentmoldwhic-h is open at its bottom, rentin theyaiitrappea; in; the moldand causing the slip to riseinto preparatory to finishand described thepreferred apparatus and process for carrying outfmyinvention, it is tobe understood that the invention is not solimitedbut-may be otherwiseembodied and practiced within the until a fsemi-SOlidcoherent lay'er' ofceramic, material is deposited against -theabsorbent} mold surfaces, 5and then removing the {mold 125 2. The process of casting'cerainicarticles, 7 Y which comprises dippinginto abath of -fluid ,j. i stingceramic "articles; which-comprises dipping into a bath of fluidceramie'slip a wateriabsorbent moldwhich is and fill the mold cavity andremain therein until a semi-solid coherent layer of ceramic material isdeposited against the absorbent mold surfaces, raising the mold from thebath, and allowing the excess slip to drain therefrom.

3. The process of casting ceramic articles,

- which comprises dipping into a bath of fluid ceramic slip a waterabsorbent mold which is open at its bottom, venting the air trapped inthe mold and causing the slip to rise into and fill the mold cavity andremain therein until a semi-solid coherent layer of ceramic material isdeposited against the absorbent mold surfaces, raising the mold from thebath and allowing the excess slip to drain therefrom, drying thematerial deposited in the mold, and removing it therefrom.

&. Apparatus for casting ceramic articles, comprising a tank holding afluid bath of ceramic slip, and a water absorbent mold adapted to bedipped into the bath having a moldcavity open at the bottom to allow theceramic slip to rise into the mold when immersed.

5. Apparatus for casting ceramic articles, comprising a tank holding afluid bath of ceramic slip, and a water absorbent mold adapted to bedipped into the bath having a mold cavity open at the bottom to allowthe ceramic slip to rise into the mold when immersed and a vent at thetop of the cavity to allow the escape of entrapped air.

In testimony whereof I have hereunto set 7 my hand.

a BERNARD S. PURINTON.

